worm/virus infestation

I'm having a problem w/ my laptop. I believe it has a worm that has infected it. I can't acces any of my files, programs, or utilities, including System Restore. I talked to Dell technical support, but they said that the only thing i can do is to reload the operating system back on. The only thing w/ that is that i have very precious picture files on my hard drive that I can't lose or i am screwed. I asked them what they though it could be, and they said 3 causes. Antispyware, virus, or this other thing. It couldn't be both, because i have an antispyware program, and my router and wireless card both have firewalls. But the third cause blew my mind. That there was this other sort of being in my computer remotely accessing my system, and disobeying my commands. What could this be? I really need to back my files though, that's all i care about.